The disclosure relates to an electronically slip-controllable vehicle brake system. A slip-controllable vehicle brake system of this kind is known from DE 199 40 263 A1, for example. This known vehicle brake system comprises an antilock control system, a traction control system and an electronic stability control system. Whereas, in the case of an antilock control operation, the driver produces the brake pressure in a wheel brake by actuating a brake master cylinder by muscle power, this brake pressure is produced at least partially by external force in the case of a traction control operation and a stability control operation. For this purpose, the vehicle brake system is provided with a pressure generator, which is driven by an electronically actuable electric motor.
Between the brake master cylinder and the wheel brake of the known vehicle brake system, there is a first pressure medium connection that can be controlled by a changeover valve. In its normal position, the changeover valve is an open directional control valve having two pressure medium ports, which can be switched over from the through flow position into a shutoff position. In the shutoff position of the changeover valve, the hydraulic connection between the driver and the wheel brake is interrupted, and therefore the brake pressure can no longer be changed by the driver.
There is a second pressure medium connection between the brake master cylinder and a suction side of the pressure generator. This pressure medium connection can be controlled by means of an “intake” valve. This intake valve is a directional control valve that is closed in its normal position and has two pressure medium ports, which valve can be switched over from a shutoff position into a through flow position in order to enable the pressure generator to be supplied with pressure medium from the brake master cylinder when required.
The intake valve and the changeover valve are designed as two 2/2-way valves which are structurally separate from one another and can each be switched over by an associated electronically actuable actuator. This mode of construction is relatively complex, requires duplicated assembly work for anchoring the two valves on a housing block of a hydraulic unit of the vehicle brake system, takes up a relatively large amount of installation space in this housing block and is furthermore expensive.
The description of DE 199 40 263 A1 contains the indication that it is also possible to use a common 3/3-way valve instead of two individual 2/2-way valves. However, this indication relates to the pressure buildup and pressure reduction valves, i.e. to the device for modulating the brake pressure in the wheel brake, and not to a combination of a changeover valve with an intake valve in a vehicle brake system with electronic stability control (ESP brake system).